I believe the battery issue depends whether they're nickel cadmium (bad) or nickel metal hydride (not so bad). My understanding is that most hybrids today use NMH batteries. which can be recycled. The manufacturers claim they'll last for 150,000 to 200,000 km, but a bit of web searching reveals stories of people who've had to have them replaced earlier - most of those, I think, are slightly older-model hybrids, however, so possibly some of the problems are being worked out. The first story I came up with of someone having his hybrid car battery die was this one, from 2006, driving a 2000 Insight, still under warranty - several people in his comments relate similar stories, and one mentions a $5000 battery replacement cost, because the car in question was no longer under warranty.

So, basically, like almost any other car matter, it depends on the particular car and the type of warranty you get on it ;)